The nighttime detour of Main Street downtown will last until the middle of next week, according to a spokesman for Columbia Gas of Massachusetts.

Charles Winokoor

The nighttime detour of Main Street downtown will last until the middle of next week, according to a spokesman for Columbia Gas of Massachusetts.

The company is in the midst of replacing 1880s cast-iron pipes underneath downtown streets with modern high-density, polyethylene plastic piping.

Traffic at night has also been diverted away from Weir Street at Taunton Green heading toward High Street, so that workers from Saccone Bros. Inc. can continue repairing, upgrading and sometimes replacing aged sewer pipes in the Silver City.

That ongoing effort is part of a city-wide project to eliminate the occurrence of “combined sewer overflow” (CSO) that typically empties into Taunton River during heavy rainfall.

To date, the Department of Public Works has been granted more than $55 million in low-interest, state revolving loans to improve the sewer system — in order to comply with a state and federal compliance order to eliminate all CSO. The city has 20 years to pay off the percent loans.

The Weir Street work is being done at night, according to DPW water division supervisor Cathal O’Brien, because city-wide sewer flow is lower then compared to daytime hours.

There’s also been ongoing infrastructure work during the day on Main Street, as part of the city’s $2.1 million Downtown Sidewalks Improvement Project.

That construction project began in June 2012 and has already resulted in new sidewalks extending from Leonard Court down Broadway and over to Post Office Square. A newly designed pedestrian crossing has been installed near Taunton Green and parking kiosks have replaced meters.

Phase Two of the project, which got underway in July, is “slightly ahead of schedule,” according to Jim Howland, project manager for the city’s department of economic and community development.

Workers for LAL Construction of Fall River have been excavating old sidewalks on the north side of Main Street stretching from Union to Trescott streets. Howland said School Street from Main to Fruit streets now has new sidewalks, and added that Knotty Walk closer to the Green is refurbished.

“It’s gorgeous,” he said of the new and improved Knotty Walk.

Howland also noted that curbs have been elongated at some corners so that entering a crosswalk is safer.

Parking is prohibited on Main Street’s north side and will continue to be at least through next week until work has wrapped up, Howland said. He said work on the south side will most likely be finished, weather permitting, by the first week of October.

Subsequent work, he says, will involve new sidewalks in front of El Mariachi restaurant, the so-called bull-nose area in front of Isabella’s Bridal and one side near the Post Office that still needs to be replaced.

All concrete for those sites will be set and in place by the time the city holds its annual Lights On on Dec. 15, he said.

By installing new sidewalks the city is finally ridding itself of the nuisance and liability of uneven, decorative “concrete pavers” that for years have caused problems for pedestrians.

Howland said come springtime trees will be re-planted. He also said Broadway Arcade, that provides a connection from Broadway to a rear parking area and a cut-through to School Street, will be transformed into an asphalt roadway at around the same time.

Howland said downtown business owners have been cooperative and understanding.

“It’s always a plus when that’s the case,” he said. “They’ve been tolerating all the noise and dust and stuff.”

The city is not paying for the sidewalks improvement project. A total of $1.3 million was provided by MassWorks Infrastructure Program funding. The balance came from federal Community Development Block Grant funding.